Foaming is an important property of lubricating oils and the like automotive liquids. A tendency of a lubricant to foam adversely affects the lubricating properties of the oil by reducing oil circulation within an engine, possibly leading to losses of oil and enhancing oxidation. The tendency of an oil to foam at elevated temperatures can cause pump cavitation and is a serious problem also in splash lubrication, high speed gearing, and similar uses. Inadequate lubrication and overflow loss of lubricant are factors that can lead to premature mechanical failure.
Accordingly, for quality control purposes it is important to be able to evaluate the foaming tendencies of lubricating oils, hydraulic fluids, and the like.
While foam testing devices are known in the art and standards for foam testing, such as ASTM Standard D892, have been established and have undergone revisions from time to time, reliable foam measurements continue to be challenging. Existing foam testing devices continue to exhibit shortcomings such as bulkiness of the device, difficulty in operation, difficulty in handling oil samples to be tested, relatively long test period duration, reproducibility of test results.
The present invention provides an improved foam test apparatus that ameliorates the aforedescribed shortcomings, is compact, easy to use, and provides consistent, readily reproducible foam test results.